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Abstract & Commentary
Synopsis: Excessive hindfoot pronation as determined by the navicular drop measure was correlated with MTSS.
Source: Bennett JE, et al. Factors contributing to the development of medial tibial stress syndrome in high school runners. J Orthop Sports Phys Ther. 2001;31(9):504-510.
For years now, running has been the activity of choice for many competitive and recreational athletes. This population is highly susceptible to overuse injuries. One such injury is medial tibial stress syndrome, described as pain over the medial aspect of the distal two-thirds of the tibia. This pain occurs essentially due to unknown etiology. In fact, stress fractures and posterior compartment syndrome are not considered part of this syndrome. There is some overlap with the term "shin splints," and any medical practice that includes runners will include medial tibia stress syndrome (MTSS). Speculation regarding etiology has long included biomechanical abnormalities such as increased foot pronation and other possible structural abnormalities such as tibia varum and excessive forefoot supination.
One of the primary purposes of this study was to determine the relationship between these conditions, as measured by typical, low-tech, clinical measures, and the incidence of MTSS. The original sample included 125 cross-country runners from 3 high schools. This included 57 males and 68 females. During the course of 1 season, coaches and athletic trainers who suspected MTSS referred the patients for evaluation. If MTSS was confirmed, the athlete was included in the study. By the end of the season, 15 subjects provided 25 limbs for inclusion in the study. A control group was selected randomly from asymptomatic runners. Lower extremity measures included navicular drop (to measure relative hind foot pronation), resting calcaneal position, tibiofibular varum, and gastrocnemius length as measured by ankle dorsiflexion (with a goniometer). Reliability studies were done prior to the measurements and subjects were blinded to the measurer for all measures. In addition, demographic characteristics such as age and sex were correlated to the injury.
A stepwise logistic regression analysis determined that navicular drop (hind foot pronation) and sex (13 of 15 injured subjects were female) made up 76% of the formula necessary to predict injury. In other words, these 2 variables may be strong contributing factors to MTSS.
Comment by Clayton F. Holmes, EdD, PT, ATC
Speculation regarding the etiology of lower extremity overuse injuries has long centered on biomechanical considerations such as an "over-pronated" foot. This excellent study lends to the credibility of this speculation. Evidence is mounting that suggests that abnormal foot or lower extremity alignment contributes to overuse injuries such as MTSS. The implications include the use of orthotic therapy to treat these conditions and prevent these conditions in a high-risk population. The measure used in this study, the navicular drop, has been shown to be the most reliable clinical measure of rear foot pronation, and it is a common measure performed by physical therapists. Hopefully, this type of evidence will influence many third party insurers to pay for orthotics in this population. Currently, this is not the case.
It is also interesting to note that more females than males are susceptible to MTSS. While this has certainly not been the case in my experience, it may further delineate an at-risk group.